Zhang Hui-na, Lin Zhi-bin
Department of Pharmacology, School of Basic Medical Sciences, Peking University, Beijing 100083, China.
Acta Pharmacol Sin. 2004 Feb;25(2):191-5.
To investigate the hypoglycemic effect of Ganoderma lucidum polysaccharides (Gl-PS) in the normal fasted mice and its possible mechanism.
Normal fasted mice were given a single dose of Gl-PS 25, 50, and 100 mg/kg by i.p. and the serum glucose was measured at 0, 3, and 6 h after administration. Gl-PS 100 mg/kg were also given by i.p. and the serum glucose and insulin levels were measured at 0 min, 30 min, 1 h, 3 h, 6 h, and 12 h. Pancreatic islets were isolated and incubated with glucose 5.6 mmol/L and different concentration of Gl-PS, the insulin content of islets and insulin release were examined. The islets fluorescent intensity of [Ca2+]i was also studied with a confocal microscope. Verapamil and egtazic acid were used to testify whether the insulin-releasing effect of Gl-PS was mediated by its ability to raise the Ca2+ influx.
Gl-PS dose-dependently lowered the serum glucose levels at 3 h and 6 h after administration. Gl-PS 100 mg/kg raised the circulating insulin levels at 1 h after administration. In vitro, Gl-PS had no effect on islets insulin content, but it stimulated the insulin release after incubation with glucose 5.6 mmol/L. Confocal microscope showed that Gl-PS 100 mg/L had the capacity to raise the [Ca2+]i. The insulin-releasing effect of Gl-PS was inhibited by verapamil/egtazic acid.
Gl-PS possesses the hypoglycemic effect on normal mice; one mechanism is through its insulin-releasing activity due to a facilitation of Ca2+ inflow to the pancreatic beta cells.
研究灵芝多糖（Gl-PS）对正常禁食小鼠的降血糖作用及其可能机制。
正常禁食小鼠腹腔注射25、50和100mg/kg的单剂量Gl-PS，并在给药后0、3和6小时测量血清葡萄糖。还腹腔注射100mg/kg的Gl-PS，并在0分钟、30分钟、1小时、3小时、6小时和12小时测量血清葡萄糖和胰岛素水平。分离胰岛并与5.6mmol/L葡萄糖和不同浓度的Gl-PS一起孵育，检测胰岛的胰岛素含量和胰岛素释放。还用共聚焦显微镜研究胰岛[Ca2+]i的荧光强度。使用维拉帕米和依他酸来验证Gl-PS的胰岛素释放作用是否由其增加Ca2+内流的能力介导。
Gl-PS给药后3小时和6小时剂量依赖性地降低血清葡萄糖水平。100mg/kg的Gl-PS给药后1小时提高循环胰岛素水平。在体外，Gl-PS对胰岛胰岛素含量无影响，但与5.6mmol/L葡萄糖孵育后刺激胰岛素释放。共聚焦显微镜显示100mg/L的Gl-PS有增加[Ca2+]i的能力。维拉帕米/依他酸抑制了Gl-PS的胰岛素释放作用。
Gl-PS对正常小鼠具有降血糖作用；一种机制是通过促进Ca2+流入胰腺β细胞而发挥其胰岛素释放活性。
